Officer in charge of Chattogram railway police station Md Nazim Uddin confirmed the development.
Meanwhile, the railway authorities have suspended Saddam temporarily.
Railway east zone’s divisional railway manager (DRM) Abul Kalam Azad told Prothom Alo that Saddam was suspended as the police detained him for negligence.
Tough action would be taken against gateman Saddam if the probe committee finds his negligence, he added.
Police and eyewitnesses Chattogram-bound Pravati Express train rammed a microbus that was returning from Khaiachara waterfall in Mirsharai with 15 tourists. The train rammed into the vehicle and dragged it about a kilometre away.
Witnesses and passangers of the train allege that there was no barrier in place as the gateman was absent during the accident.